You don’t need to do a lot of abdominal crunches in order to firm your abdominal muscles. It’s the intensity of the exercise that tones the muscle. Try this simple exercise to tone your tummy*:
Seated on a bench or backless chair bring your legs straight out in front of you with your heals touching the ground. Sit tall and cross your arms in front of your chest. Next lean back till you feel your ab muscles tightening (or quivering). Inhale then exhale come back up to a seated position. Repeat 15-20 reps. Now pretend that you are holding a small ball. Slightly twist leading with your elbow to the right. Repeat 15-20 reps then switch sides. Work up to two complete sets (center, rt. side, lft. side).
*Please note that these exercises will firm your muscles, but in order to see muscle definition body fat has to be lost through a combo of cardio exercise and eating healthy.